1. Field of the Invention
The present invention relates to a composition for a polishing pad and a polishing pad using the same, and this polishing pad can be suitably utilized for polishing the surface of semiconductor wafer and the like.
2. Description of the Related Art
As a method for polishing which can form the surface having the high flatness, an attention has been recently paid to CMP (Chemical Mechanical Polishing). In CMP, polishing is performed by flowing down a slurry which is an aqueous dispersion in which abrasives are dispersed to the surface of a polishing pad from an upper side while sliding a polishing pad and a side to be polished.
A factor which has a great influence on the productivity in this CMP is the removal rate and, this removal rate is expected to be improved remarkably by setting at a greater amount of the retained slurry than previously used amount.
Hitherto, in CMP, a polyurethane foam containing fine air bubbles has been used as a polishing pad, and polishing has been performed by retaining a pore opened on the surface of this resin (hereinafter, referred to as xe2x80x9cporexe2x80x9d).
However, in the polyurethane foam, it is difficult to control the foaming freely, and it is extremely difficult to control a size of foamed air bubbles, a foam density, and the like through the foam uniformly. As a result, the quality of a polishing pad comprising a polyurethane foam varies, leading to the cause for the varied removal rate and the procession state.
As a polishing pad in which controlling of a pore is easier upon this foaming, there are known soluble materials dispersed in a number of resins described in Japanese Patent laid-open publication Hei 8-500622, Japanese Patent laid-open publication 2000-34416 and Japanese Patent laid-open Publication 2000-33552, and the like. Among them, the effectiveness of a polishing pad containing solubles materials is suggested in Japanese Patent laid-open publication Hei 8-500622 and Japanese Patent laid-open publication 2000-33552. However, a matrix material is not studied when it is actually used as a polishing pad.
In addition, a component material is studied in Japanese Patent laid-open publication 2000-34416 and the more stable polishing and an improvement in the removal rate are recognized but a further improvement in the slurry retaining properties and the polishing rate is required.
The present invention was done in view of the aforementioned circumstances, and an object of the present invention is to provide a polishing pad which has the great removal rate due to the excellent slurry retaining properties, and can effectively prevent a decrease in the retaining properties and the removal rate during polishing and even after dressing, and a composition for a polishing pad which can form such the polishing pad.
The present inventors studies in detail the mechanism by which the slurry retaining properties and the removal rate are gradually decreased during polishing, and the mechanism in dressing in which a pore is formed (face forming) or updated (face updating) on the surface of a polishing pad with a diamond whetstone and the like. As a result, we found that, when shear stress is exerted on the previous polishing pad surface by the polishing, dressing and the like, an elongation produced on the surface of a matrix material which is a main component material and, thereafter, the surface is deformed plastically and, thus, a pore is choked. Further, we found that since dusts of not only surface of a wafer but also a matrix material itself are produced, these dusts also choke a pore. That is, we found that a sufficient improvement in the removal rate can not be effected for these causes and, as a method for preventing them, the use of a material having the cross-linking structure manifesting the elastic recovery in a matrix material is effective, which resulted in completion of the present invention.
The present invention is based on the findings described above and can be described as follows.
1. A composition for a polishing pad which comprises a water-insoluble matrix material containing a crosslinked polymer and a water-soluble particle dispersed in the water-insoluble matrix material.
2. The composition for a polishing pad according to 1 above, wherein the elongation remaining after breaking is 100% or less when a test piece comprising the water-insoluble matrix material is broken at 80xc2x0 C.
3. The composition for a polishing pad according to 2 above, wherein said water-insoluble matrix material is modified with at least one selected from the group consisting of an acid anhydride group, a carboxyl group, a hydroxyl group, an epoxy group and an amino group.
4. The composition for a polishing pad according to 3 above, wherein said water-soluble particle is an organic water-soluble particle comprising at least one selected from the group consisting of dextrin, cyclodextrin, mannit, lactose, hydroxypropylcellulose, methylcellulose, starch, protein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyethylene oxide, water-soluble photosensitive resin, sulfonated polyisoprene and sulfonated polyisoprene copolymer, and/or an inorganic water-soluble particle comprising at least one selected from the group consisting of potassium acetate, potassium nitrate, potassium carbonate, potassium bicarbonate, potassium chloride, potassium bromide, potassium phosphate and magnesium nitrate.
5. The composition for a polishing pad according to 4 above, wherein the amount of said water-soluble particles is 10 to 90% by volume based on 100% by volume as the total amount of said water-insoluble matrix material and said water-soluble particles.
6. The composition for a polishing pad according to 1 above, wherein at least a part of said crosslinked polymer is a crosslinked rubber.
7. The composition for a polishing pad according to 6 above, wherein at least a part of said crosslinked rubber is crosslinked 1,2-polybutadiene.
8. The composition for a polishing pad according to 7 above, wherein said water-insoluble matrix material is modified with at least one selected from the group consisting of an acid anhydride group, a carboxyl group, a hydroxyl group, an epoxy group and an amino group.
9. The composition for a polishing pad according to 8 above, wherein said water-soluble particle is an organic water-soluble particle comprising at least one selected from the group consisting of dextrin, cyclodextrin, mannit, lactose, hydroxypropylcellulose, methylcellulose, starch, protein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyethylene oxide, water-soluble photosensitive resin, sulfonated polyisoprene and sulfonated polyisoprene copolymer, and/or an inorganic water-soluble particle comprising of at least one selected from the group consisting of potassium acetate, potassium nitrate, potassium carbonate, potassium bicarbonate, potassium chloride, potassium bromide, potassium phosphate and magnesium nitrate.
10. The composition for a polishing pad according to 9 above, wherein the amount of said water-soluble particles is 10 to 90% by volume based on 100% by volume as the total amount of said water-insoluble matrix material and said water-soluble particles.
11. The composition for a polishing pad according to 1 above, wherein said water-soluble particle is provided with an outer shell for inhibiting moisture absorption in at least a part of the outermost part.
12. The composition for a polishing pad according to 11 above, wherein said water-soluble particle is an organic water-soluble particle comprising of at least one selected from the group consisting of dextrin, cyclodextrin, mannit, lactose, hydroxypropylcellulose, methylcellulose, starch, protein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyethylene oxide, water-soluble photosensitive resin, sulfonated polyisoprene and sulfonated polyisoprene copolymer, and/or an inorganic water-soluble particle comprising of at least one selected from the group consisting of potassium acetate, potassium nitrate, potassium carbonate, potassium bicarbonate, potassium chloride, potassium bromide, potassium phosphate and magnesium nitrate.
13. The composition for a polishing pad according to 12 above, wherein the amount of said water-soluble particles is 10 to 90% by volume based on 100% by volume as the total amount of said water-insoluble matrix material and said water-soluble particles.
14. A polishing pad characterized in that at least a part of said polishing pad comprises the composition of a water-insoluble matrix material containing a crosslinked polymer and a water-soluble particle dispersed in the water-insoluble matrix material.
15. A polishing pad according to 14 above, wherein the elongation remaining after breaking is 100% or less when a test piece comprising the water-insoluble matrix material is broken at 80xc2x0 C.
16. A polishing pad according to 15 above, wherein the Shore D hardness is 35 or more.
According to the present invention, there can be obtained a composition for a polishing pad which can afford a polishing pad in which a pore is formed in the better state, a pore is not choked even by dressing, and the slurry retaining properties are better. And also, there can be obtained a composition for a polishing pad in which a water-soluble particle contained in said polishing pad does not absorb moisture and is not swollen, and which can afford a polishing pad having the high hardness. In addition, according to the invention, there can be obtained a polishing pad which can perform polishing at the high removal rate.